Does it only toggle when you are trying to change it via google home?
I’m really not familiry with teh MIIO / Xiaiomi binding, but could the keyword “toggle” in your channel be the problem? Maybe the binding interprets that as a switch that toggles the state everytime it received the ON command.
Yes, you do implement such workaround
You will need to use a “dummy” item that will receive the commands and then with a rule, you will “filter” the commands to the “real” item.